A professor of criminology at New York University, karate black belt, and licensed private investigator, Robert Frederickson would seem a run-of-the-mill literary detective. But Frederickson is a dwarf, whose first career was as a circus acrobat, billed as Mongo the Magnificent. Mongo was the creation of George Chesbro, who has died aged 68, and featured in 15 novels whose plots were over-the-top concoctions of science fiction, fantasy, and hi-tech spy thrillers, laced with irony and satire, and whose critical acclaim was often qualified by the phrase "acquired taste".

Although he published some 27 novels and more than 100 short stories, Chesbro's writing career experienced severe troughs. Born in Washington DC, he grew up in Delmar, New York, and graduated from Syracuse University with a teaching degree. He spent 17 years working with students with learning disabilities. As a student himself he began suffering from bouts of severe depression, and took up writing, which he called his "dark engine". It took him years to make his first sale, a poem for $1, but in 1976 he published his first novel, the spy thriller King's Gambit, which appeared as a paperback original in Britain.

The first Mongo novel, Shadow of a Broken Man, appeared the following year, from Simon and Schuster in the US. The idea of a dwarf detective struck Chesbro when he had noticed the popularity of television detectives such as Ironside (in a wheelchair) or Longstreet (blind). Originally, he considered the comic possiblities, but could not make them work. Then, as he explained: "The damn dwarf just wouldn't go away... I gave Mongo his dignity and he gave me a career."

Chesbro turned to writing full time, but after Mongo's third outing, An Affair of Sorcerers (1979), his publisher dropped him. He found work as a motel security guard and took occasional teaching jobs until Mongo reappeared in The Beasts of Valhalla (1985). However, he had also been contracted to produce a paperback series under the name David Cross. His original concept, Veil Kendry, an army veteran with psychic powers, was rejected as "too cerebral", so he wrote three more books featuring John "Chant" Sinclair, and sold the two Veil novels elsewhere. Veil and Chant would both appear in the Mongo series, and Chesbro would write Veil short stories, as he also did stories featuring Mongo's brother Garth. This was the peak of his productivity. With two more Mongo novels and the adaptation of the Eddie Murphy film The Golden Child, Chesbro published no fewer than nine novels between 1985 and 1989.

Seven more Mongo novels followed, one a year, the last two with Simon and Schuster, who again dropped him after his 14th, Dream of a Falling Eagle (1996). However, virtually all of his works were already out of print in the US.

Divorced twice, Chesbro was living a reclusive life in Nyack, New York, when he married his third wife, Robin, a childhood friend, in 1997. They set up their own publishing house, Apache Beach, bringing his work back into print, collecting his short stories, and publishing two further works in 2001.

A film version of The Beasts of Valhalla, for which Chesbro wrote a screenplay, is in production, with Peter Dinklage in the lead. A 15th Mongo novel, Lord of Ice and Loneliness, was published in France in 2006 but could not find a US publisher.

Chesbro is survived by his wife, two children from his first marriage and two stepchildren from his third.

• George Clark Chesbro, writer, born 4 June 1940; died 18 November 2008